Data recording and error detection system



Nov. 7, 1967 R. E. MILFORD 3,351,919

DATA RECORDING AND ERROR DETECTION SYSTEM Filed May 19, 1965 18 Sheets-Sheet 1 22b READER READER PUNCH TELEPHONE PUNCH FACILITY q 0 A 4?}; DATA SET DATA SET 25 CENTRAL PROCESSOR mvmv'roa RICHARD E. MILFORD BY ATTORNEY R E. MILFORD Nov. 7, 1967 DATA RECORDING AND ERROR DETECTION SYSTEM 18 Sheets-Sheet 3 Filed May 19, 1965 7 INVERSE RE- DUNDANT ans TDATA BITS C|-|ARACTER FRAME- MARK CHARACTER FRAME Nov. 7, 1967 R. E. MILFORD 3,351,919

DATA RECORDING AND ERROR DETEL'TJON SYSTEM Filed May 19, 1965 18 Sheets-Sheet 4 TEST TERMINAL CI CONNECTORS BUSINESS MACHINE LINE INTERLOCK mm'o INTER LOCK mm:

JDNT t 40 -l8V TO 2' 56 READER/ PUNCH 24V H74 55% awn-{ 1- DATA SET 5| I; neAoen/ uucn DATA SET CE JDR a aw g REMOTE 44 66 CONTROL DATA SET READY SIGML RING 2 JDRZ 62 TO DATA SET POWER RELAY KPWR ov Q Nov. 7, 1967 R. E. MILFORD 3,351,919

DATA RECORDING AND ERROR DETECTION SYSTEM Filed May 19, 1965 18 Sheets-Sheet 5 COMMUNICATION CONTROL LOGIC 9| 5 RE u 92 a? Q EST Sfii Q F 93 FRSDI TO SEND aouoo s FDPXI DUPLEX L px 99 MODE IEEID 00cm R o FDPXO SGML EDGE *1 l0 FXMEI 0X mall I 8 aw F6020 SEC DELAY 52 o "2 FWD-O'- 97 R 0 TW SPACE s m km 2 99 mglmo FXME mono MARKER s m $252250 'E%%E IDTCXI Q E o 2 CLOCK GENERATOR Mk0 0mm om; m DCSTI 0 omnko Kmro I 00020 o-F fgfi' ocno OOFCOZI FCO5I o Nov. 7, 1967 R. E. MILFORD DATA RECORDING AND ERROR DETECTION SYSTEM Filed May 19, 1965 BIT COUNTER FCOII FCOZI j g O 6 0 LL IO 0 a 5-35 u. E

O 8 o O E O 8 8 o i u a 18 Sheets-Sheet 6 II II; I; ll; 1.; I;

18 Sheets-Sheet 7 Nov. 7, 1967 R. E. MILFORD DATA RECORDING AND ERROR DETECTION SYSTEM Filed May 19, 1965 S80 256x006 w 280 ZzQwVGQd 0 R. E. MILFORD Nov. 7, 1967 18 Sheets-Sheet 8 Filed May 19, 1965 dam! m2 we ammo MM 2 2. TE- Em E5 5655 B All! :65 a

2.. b b NJ b P b m0- 8 8a GM 26 OM80 8 8a 88o OM80 H m o m o m o m o m L, o m 3 2m. DIE $9 22 2E 22 m m w w m m 36a 5%. 5 2 51$ IQ =5. C 4L t 1L g f- L 32L mm. :2 L 0 mm. 3m. 3m. 82 3 G 8. 3. an 3 2238 N 2238 n 2238 E n 2238 2238 B 2:38 52%. 53mm 53mm 1 35: EQH $051 20E 20E :3. 3. 28. :2: :9; 88 58 g 268 82:

Nov. 7, 1967 R. E. MILFORD 3,351,919

DATA RECORDING AND ERROR DETECTION SYSTEM Filed May 19, 1965 18 Sheets-Sheet l0 FLOW CHART 0F READ OPERATION START REsET FSRH READ 7 OR IS coum.

YES TEST FOR wAs RECEIPT YES TAPE LEADER ACKNOWLEDGED? SET TAPE In men @569 A'QT TRANSMIT. N0 N0 STARTCLOCK RESET N0 TEST FDR SET RESET lP-F FLIP-FLOP GENERATOR. COLUMN 8 F mm 4, YES} i SET TAPE TT8 30 SET FLIP- SET FLIP- TER LEADER FLIP DELAY FLOP FLOP mATE -FLOP FTLD. FMOB. FTRD. READ. ISEETADSTART s Efi FLI P r V R D TRANSMIT READ BACK EA QE'ZQE? FIRST zERo ONE BLOCK 1 IS DELA START RESET RESET SEARCH CLOCK FLI P- FLOP FLIP-FLOP COMPLETE? mos. FrRD.

YES

TRANSFER TRANSMIT RESTART DATA TO 2ND ZERO RIER $H|FT REG, OF COLE. EXCHANGE.

INHIBIT 58;? F so T0 N0 3 mm; YES y 7 RESET #3 DATA FLlP- FLOP LINE. DATA SET FRsD.

I, CARREER STOPS.

Nov. 7, 1967 Filed May 19, 1965 START QDCK GENERATOR SET FUP FLOP F PUT R. E MILFORD DATA RECORDING AND ERROR DETECTION SYSTEM 18 Sheets-Sheet l3 CHARACTER.

SEI' FLIP-FLOP FSTP.

START PUNCH.

OENAI TO PUNCH REGISTER H10 PUNCH REGISTER RESET.

RECEIVE RECEIVE DUPLICATE DUPLICATE CHARACTER. CHARACTER.

PUNCH PUNIEH H R c SPROC ET c A A TER ON ERROR? YES SIGNAL ss'r FLIP- TTS 3| FLOP FERRAT GENERATED coum l.

RESET HOLD PUNCH. FLIP-FLOP REGISTER FSTE RESET. 1

SET FLIP- FLOP FPWS AT IGCT RECEIVE SECON D ZERO CODE.

START PUNCH PUNCH SPROCKET ONLY.

R. E. MILFORD Nov. 7, 1967 DATA RECORDING AND ERROR DETECTION SYSTEM 18 Sheets-Sheet 14 Filed May 19, 1965 ommmu ram mmJDa x0040 .SOIPE mm 5m Fmmo 00 man 6000 75mm 2004 Om .ZOo 1023a R. E. MILFORD Nov. 7, 1967 18 Sheets-Sheet 15 Filed May 19, 1965 88a :55 E80 212 7 3 e2 25E 0 m 0E2 mm o m H. m wo 12 58. C E5 E5. r E Fll S m: h. :5. 63

QQOJ IQZDQ mommw Nov. 7, 1967 R. E. MILFORD DATA RECORDING AND ERROR DETECTION SYSTEM 18 Sheets-Sheet 't 7 Filed May 19, 1965 .ozna r Fxwml 65m azwhTl Grwml Ermml -:m. ll =5. l .Qua l .wRxTl omouoll, 505 1 58 58. .1 $09. 1 597 68% ONOOOJ 0500'... 0360' mmhu m xu PmEu woou OmuN .65.

Nov. 7, 1967 R. E. MILFORD 3,351,919

DATA RECORDING AND ERROR DETECTION SYSTEM Filed May 19, 1965 18 Sheets-Sheet 18 3 5 65 & 3 5 2 5 K. g o E TIMING CHART END OF BLOCK I I I I I I I |--F|RsT ZERO cooE I sEco-0 ZERO cone Unitcd States Patent Office 3,351,919 Patented Nov. 7, 1967 3,351,919 DATA RECORDING AND ERROR DETECTION SYSTEM Richard E. Milford, Phoenix, Ariz., assignor to General Electric Company, a corporation of New York Filed May 19, 1965, Ser. No. 456,949 15 Claims. (Cl. 340l72.5)

TABLE OF CONTENTS General Description Statement; of the Inventiorn. Brief Description of Drawing Glossary and Index of Signals... l.

Data Communication System Operation Line Direction Control Data Transmit Sequence Data Receive Sequence. .i Transmission of 5, t5 and 7 Level Codes Error Detection 'lope Operating Parameters lliork of llatn EurLoHJata-Bloek Marker.

Data Sets...

Description Attended Data Set Operation cacoooq zqqcamcamonnu -w' Unattended Data Set Operation" Logic Components. 1 Flip-Flop AND-(late l1 OR-Untrn, 1: Inverter 2 Communication Control Logic 12 Request to Send Data l2 Establishing Communication. 12 'lerminating Commnnir-ation. 14 Communication Interrupts. 14

Clock Generator and Bit Connie l Shift Regisler. 17

Description of Read Tape Mode of Operation. 19

Start. (lock Generator lransmi sion of First (fode... 2t) Set Tape Leader Flip-Flo1J lFlLl) 21 StzirtRcaderSearclL. 22 End-oLBlor-k Recognition. 22 Read Termination Function. 23 Retransmission of Datum. 24 Description of Punch 'lape Mode of Operation 24 Rcceiptof First Zero (1ode...i. 25 Receipt of Non-Zero Character 25 Error Circuitry" 27 Receipt of E|1d-oi-l)ata Block l i 28 GENERAL DESCRIPTION Statement of the Invention This invention relates to data communications and more particularly to terminal equipment for use at the ends of message networks for receiving and transmitting data to and from business machines which may form a part of an electronic data processing system.

As business enterprises expand geographically to multipoint operations, the transmission of large volumes of data by mail is found to be too slow and by voice impractical. The use of telegraph for data transmission has been satisfactory in many instances; however, the concurrent requirements for data communication and data processing has resulted in the need for an economical terminal which may receive and transmit data automatically over telephone networks.

In many instances, multi-computer sites have been utilizcd to provide management control of multipoint operations with the resulting benefits of electronic data processing at each of the sites. However, this form of business management involving a plurality of computer sites is expensive and unprofitable if the multipoint operations cannot fully utilize the capacity of the computers. Thus, it is obvious to management of small as well as large multiplant operations that a centralized computer operation is economically desirable if it can be shared with each of the operations at the various sites.

To date, many firms in the business machine, ofilcc equipment and communication equipment fields have devcloped and marketed digital data communication devices. Most operate in conjunction with the common carrier facilities of the telephone and telegraph lines.

It is not enough, however to merely convert information to digital form and then transmit the information from one site to another. The information in digital form must be transmitted from one business machine to another over the selected transmission line at the baud rate of the line. In addition to the transmission rate and rate capacity of the system, the accuracy of the information transmitted from one business machine to the other must be of a sufficient high order to warrant reliability. Accuracy is not only a function of the operators performance but in automatic answering terminal equip merit, a high order of accuracy of the terminal equipment is necessary for proper functioning of the data communication system. Satisfactory checking system must be provided which will continually check the information being transmitted without disrupting the operation.

System intcgriy must be maintained if all the compo nent pars and related costs of the data communication system are to be justificd. Good communication systcms are much more than just point to point transmission of information. They also must be the best economical means of transferring information from one of many unattended terminals to any one of a number of computer sites. Arrangements must be made for sending and receiving the data without human intervention if the full benefits of data communication systems are to be obtained.

The data communication terminal equipment described comprises communication oriented paper tape terminals. These terminals may transmit information from punched paper tape over voice quality half-duplex common carrier or telctype transmission lines and receive information over the same lines, punching paper tape in accordance with the information received. As utilized herein, the terms information and data are synonymous.

The communication terminals will transmit 5, 6, 7 or characters per second. It will operate 1n a half-duplex mode, and by controlling the communication line, alternately send and receive information. Transmission errors are reliably detected when receiving municate with another like terminal at the tranmsission line as well as with essors.

The disclosed communication terminal is further capable of:

(1) Temporarily storing information received from the transmssioin line for a period of time if the recording structure at the receiving end of the transmission line is busy;

(2) Performing effective error detection and control by character redundancy transmission;

(3) Refraining from recording the remainder of a block of data once an error has been detected;

(4) Permitting the operator to identify an incorrect block of data; and

(5) Operating in an unattended mode.

Accordingly, it is an object of this invention to provide a new message accumulation and distribution system.

end of the associated central proc- Another obiect of this invention is to provide a new data communication paper tape terminal.

A further object of this invention is to provide a bidirectional paper tape transmission system employing novel automatic error detection and correction features.

A still further object of this invention is to provide a new paper tape transmission system which produces blank tape for the remainder of a block of data after detecting a character in error.

A still further object of this invention is to provide a new data transmission system which provides alternate transmission of blocks of data in both directions.

A still further object of this invention is to provide a receiving terminal which provides a new novel temporary storage arrangement for the received data if an associated recording device is busy.

Further objects and advantages of the present invention will become apparent to those skilled in the art as the description thereof proceeds.

Brief Description of Drawings The present invention may be more readily described by reference to the accompanying drawings in which:

FIG. 1 is a simplified block diagram of an information processing system for transferring information from one location to another via common or private carrier wire lines, cables or cable carrier facilities and embodying the invention;

FIG. 2 is an expansion of the block diagram of FIG. 1 showing information flow in the system of the present invention;

FIG. 3 is a diagrammatic illustration of a 7 bit character frame;

FIG. 4 is a diagrammatic illustration of a 5 bit character frame;

FIG. 5 is a fragment view of an operating tape containing a repetition of one character followed by an End-of-Block code signal;

FIG. 6 is a simplified block diagram of the data sets shown in FIGS. 1 and 2;

FIG. 7 is a schematic illustration of the relay latching arrangement of the data set shown in FIG. 6;

FIG. 8 is a schematic block diagram of the communication control logic shown in FIG. 2;

FIG. 9 is a schematic block diagram of the clock generator portion of the clock and bit counter block shown in FIG. 2;

FIG. 10 is a schematic block diagram of the bit counter portion of the clock and bit counter block shown in FIG. 2;

FIG. 11 is a diagrammatic illustration in chart form of the clock and timing signals provided by the clock and hit counter logic shown in FIGS. 2, 9 and 10;

FIG. 12 is a schematic block diagram of a shift register;

FIG. 13 is a simplified block diagram of the reader control logic shown in FIG. 2',

FIG. 14 is a flow chart of the read operation of the structures shown in FIGS. 1 and 2;

FIG. 15 is a diagrammatic illustration of a zero code;

FIG. 16 is a simplified block diagram of the Transmit Serializer flip-flop logic;

FIG. 17 is a diagrammatic illustration in chart form of the timing and logic signals involved in a tape reading operation;

FIG. 18 is a flow chart of the punch operation of the structure shown in FIGS. 1 and 2;

FIG. 19 is a simplified block diagram of the punch control logic shown in FIG. 2',

FIG. 20 is a simplified block diagram of the error punch logic;

FIG. 21 is a schematic block diagram of the punch register;

FIG. 22 is a diagrammatic illustration in chart form of the timing and logic signals involved in a punch operation; and

FIG. 23 is a diagrammatic illustration in chart form of the timing signals provided by the punch control logic for the End-of-Data Block recognition.

Glossary and Index of Signals In order to more readily understand the disclosed invention, the signals provided by the various system circuit elements are tabulated below.

1 Signals: Description of signals DC09 Count 9 in bit counter. DC16 Count 16 in bit counter. DC86 Count 8 or 16 in bit counter. DCOD Carrier Oil? delayed A second. 15 DCST Clock generator start. DCTI Count 1 in bit counter. DDSC Reader delayed search complete. DDCR Carrier On leading edge signal. DENA Enable input to punch register. 20 DEND End punch tape mode.

DEOB End-of-Block code. DMRK Receive Data-mark bit. DOND Carrier On delayed. DPRO Punch in Process. 23 DPUZ Punch zero or blank tape.

DSET Serial input to shift register. DSPP Start punch process. D RE Reset pulse to shift register. DSSR Set Start Search flip-flop. DT Tape Read and Clear to Send pulse.

DTCX Tape Read and Clear to Send signal. DTZR Tape Zero. DXMO Retransmit. DXMT Transmit Data to data set. DZEI Zero code from read amplifiers.

DZE Zero code in shift register. DZLC Tape Zero and leader. Bit counters 1 through 3. FD X Half-Duplex Control fiip-fion. FERR Error flip-flop.

FM08 8th Column Memory flip-flop. FP Punch Tape Mode flip-flop. FPW Punch Column 8 flip-flop. PR Reader Reverse flip-flop. FRSD Request to Send flip-flop.

a Shift register stages 1 through 7.

F HE Shift Register Error flip-flop. FSRH Start Reader Search flip-flop. FSTP Start Punch Control flip-flop. F D Read Control flip-flop.

Punch Register flip-flops for columns 1 through 8.

FXME Transmit Data Memory flip-fl p FXMT Transmit Serializer flip-flop. T Clear to Send from data set. D Search Complete from reader. JDRI Data set Ring Line 1. IDR2 Data set Ring Line 2. JDNT Energize Interlock (off-line switch). JMDA m Data set Receive Data. JNPT No paper tape signal from punch. J ND Carrier On signal from data set. JPUP Punch in Process. ]RS(18) Reader signals for columns 1 through 8. JREC Reader eject complete. KlNT Interlock relay. KRIN Ring relay. QCQl Ungated Clock Generator signal. QCQZ Gated Clock Generator signal. QCXl Start Clock Generator signal. SCIN Carrier Initiate signal from Request to Send switch. TTS3 Signal from multivibrator.

TTX3 Pulse signal. 

1. A DATA RECORDING SYSTEM FOR RECEIVING GROUPS OF SIGNALS WHEREIN EACH SIGNAL REPRESENTS A BINARY DIGIT, EACH GROUP OF SIGNALS COMPRISES A START SIGNAL FOLLOWED BY A PLURALITY OF SIGNALS REPRESENTING A CHARACTER AND A PLURALITY OF SIGNALS REPRESENTING THE INVERSE IMAGE OF SAID CHARACTER, A STORAGE MEANS, MEANS FOR RECEIVING SAID GROUP OF SIGNALS AND FOR APPLYING SIGNALS REPRESENTING SAID CHARACTER TO SAID STORAGE MEANS AND FOR INVERTING SAID INVERSE IMAGE OF SAID CHARACTER AND APPLYING THE INVERTED SIGNALS TO SAID STORAGE MEANS, A COUNTING MEANS COUPLED TO SAID RECEIVING MEANS AND RESPONSIVE TO THE RECEIPT OF SAID START 